Field of the Invention
The present invention relates to zoom control in an imaging apparatus used for still images or moving images. Furthermore, the present invention relates to an imaging apparatus including an optical zoom function and an electronic zoom function.
Description of the Related Art
An imaging apparatus such as a digital camera or the like includes an optical magnification variation (optical zoom) function configured by driving of a zoom lens, and an electronic magnification variation (electronic zoom) function in which a portion of an image field is enlarged. In recent years, improvements to zoom lens performance have enabled imaging with the same lens from super-wide angle to super-telephoto, and increased pixilation in the image sensor has enabled imaging with sufficient resolution characteristics even at an enlarged magnification.
On the other hand, a so-called preset zoom function and a shuttle-shot zoom function are known as functions that enable high-speed movement to the angle of view used during imaging. The preset zoom function is a function for moving from an arbitrary zoom position to a zoom position that is pre-stored in a memory by operation of a switch by a user. In addition, the shuttle-shot zoom function is a function for enhance the preset zoom function, and has a function of returning to an original zoom position. In other words, when the user operates a switch, zooming is executed from an arbitrary zoom position to a zoom position that is pre-stored in a memory, and at that time, the original zoom position is stored in the memory to thereby enable returning to the original zoom position upon completion of the preset zoom operation.
Although enlarged imaging of a distant subject is possible by use of an optical zoom function or an electronic zoom function, there is a tendency for the subject to diverge from the angle of view as a result of movement by the subject or due to strong camera shake caused by the user. In this situation, a function has been proposed for re-entering the subject into the angle of view. For example, a function has been proposed in which an optical zoom or an electronic zoom are driven in a wide-angle configuration by a predetermined amount as a result of pressing a specific button when the subject deviates from the angle of view. In this manner, the widening of the angle of view facilitates searching for the subject that was previously lost from view. When the subject is relocated, a panning operation is executed with the camera so that the subject is placed in the center of the angle of view, and then the button is released from the depressed state. In this manner, the optical zoom or electronic zoom is driven in a telephoto direction and then returned to the original angle of view.
When an FA zoom operation switch is pressed during execution of an optical zoom in the telephoto direction and an enlargement with the electronic zoom, firstly, the enlargement of the electronic zoom is released. After completely releasing the enlargement by the electronic zoom, the optical zoom is driven in the wide-angle direction, and stopped at a predetermined zoom position. When the FA zoom operation switch is released at that position, firstly, the optical zoom is driven in the telephoto direction. Then, when the optical zoom has reached the telephoto direction, enlargement with the electronic zoom is performed, and the operation is stopped at the original angle of view. There is a need during a framing assist for rapid relocation of an subject that has been lost from view. Furthermore, there is a need to rapidly return to the original angle of view after relocation of the subject so that the photo opportunity is not lost. Therefore, the speed of the zoom drive during framing assist must be increased.
Japanese Patent Laid-Open No. 2006-50019 discloses a control apparatus related to a preset zoom function and a shuttle-shot zoom function. This apparatus enables a memory zoom operation with respect to the optical zoom area and the electronic zoom area from a first zoom state in a first zoom area to a second zoom state which is a second zoom area stored in a storage unit. The apparatus disclosed in Japanese Patent Laid-Open No. 2001-117153 enables the use of different fingers when operating a first operation member for selection of a storage operation on a zoom position by the preset zoom function and a replay operation to the stored zoom position, and a second operation member for execution of an operation that is selected by the first operation member.
Japanese Patent Laid-Open No. 04-373368 discloses a method of driving the optical zoom and the electronic zoom at the same time when a zoom speed must be greater than the drive speed of an optical zoom.
The image apparatus provided with a super-high magnification zoom function may undergo a frame-out due to slight movement of the subject when adjusting the angle of view in a super-telephoto state. Furthermore, even when a user performs a small panning operation with the camera, the scope of the angle of view will undergo a large change. Under this type of super-telephoto condition, it is difficult to execute framing of a moving subject into a desired angle of view.
The preset zoom function and the shuttle-shot zoom function disclosed in Japanese Patent Laid-Open No. 2006-50019 and Japanese Patent Laid-Open No. 2001-117153 require storage of the zoom position in a memory after the user performs an operation of moving the zoom position to the desired zoom position for imaging. As a result, when tracking and imaging an subject that is moving and is out of frame, or when there is a change in the size of the subject, time is required to update the stored details in relation to the zoom position, and there is the possibility that the user will lose the photo opportunity. Furthermore, the conventional technique disclosed in Japanese Patent Laid-Open No. 2001-117153 requires user training in relation to operating methods in order to image the subject to be image at a predetermined size while tracking an subject that is out of frame. This operation requires storage of the zoom position while repeating the zoom operation with a plurality of operation members.
Furthermore, the technique disclosed in Japanese Patent Laid-Open No. 2001-117153 may cause deterioration in image quality due to an enlargement by the electronic zoom even when the optical zoom is not at the telephoto end.